Siemens SIMATIC S7-1200 - 4 PLC concepts made easy; 4.1 Tasks performed every scan cycle

Configuration and operation
5.11 STEP 7 configuration of individual parameters
CP 1243-1 PCC
Operating Instructions, 02/2015, C79000-G8976-C384-01
51
Overflow range / underflow range
Acquisition of a value in the overflow or underflow range results in the mean calculation
being stopped immediately. The value 32767 / 7FFF
h
or -32768 / 8000
h
is saved as an
invalid mean value for the current mean value calculation period and sent when the next
analog value frame is triggered. The calculation of a new mean value is then started. If the
analog value remains in the overflow or underflow range, this new value is again saved
immediately as an invalid mean value and sent when the next frame is triggered.
Note
Fault suppression time > 0 configured
If you have configured an error suppression time and then enable mean value generation,
the value of the error suppression time is grayed out but no longer used. If mean value
generation is enabled, the
error suppression time is set to 0 (zero) internally.
Set start of measuring range / Set end of measuring range
In these two input boxes, you set a limit value at the start of the measuring range and at the
end of the measuring range and if these limits are violated, the transfer of a frame is
triggered. Configuration of a threshold value trigger is necessary for this function.
The range of the value that can be configured as a decimal number corresponds to the
measuring range of the analog module (-32768 ... 32767).
By configuring these two values, you specify that the values of this analog value are
transferred as a frame only in the following situations:
● When the threshold value trigger fires
● When the value of "Set start of measuring range" is exceeded
● When the value of "Set end of measuring range" is undershot
The parameters "Set start of measuring range" and Set end of measuring range" are
pointless for measured values that have already been preprocessed in the CPU.
Note
Evaluation of the value even when the option is disabled
If you enable one or both options and configure a value and then disable the option later, the
grayed out value is nevertheless evaluated.
To disable the two options, delete the previously configured values "Start of measuring
range" or "End of measuring range" from the input boxes and then disable the relevant
option.
Recommendation for quickly fluctuating analog values:
If the analog value fluctuates quickly, it may be useful to smooth the analog value first if the
"Set start of measuring range" and "Set end of measuring range" parameters are enabled.
This avoids a frame being sent every time a limit value is violated if the analog value
fluctuates close to one of the two limit values for a longer period of time.
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